In the last few years, more and more services have been made available to mobile telephony network users. In order to facilitate the addition of new services, a mobile telephony network architecture referred to as Intelligent Network (IN) has also been devised, in which the logic adapted to implement the services (so-called service logic) is separated from the switching equipment; thanks to the IN architecture, new services can be added without having to redesign the switching equipment to support those new services.
Services implemented by INs (hereinafter also referred to as IN services) include for example voice mail routing services, pre-paid telephony services, collect-call services, and Mobile Virtual Private Network (MVPN) services. Generally speaking, the IN services provide a high degree of user convenience, as they enable to perform operations such as contacting a voice mail, decreasing in real time a credit of a pre-paid account, enabling debiting the call to the called party, or dialing a number in a MVPN via a simple operation, such as dialing a short number.
A problem of IN services is that they are normally available only from a home-network to which a particular user has subscribed. When the user's terminal roams in another network, such as a network in another country or a network which is operated by another operator, the IN services usually enjoyed in the home network may not be directly available: in particular, even if the visited network is itself an IN, implementing its own services, it may happen that these services are not made available to roaming users. Even in the case the visited network offers to the roaming users IN services similar to those made available in their home network, such services may be triggered by different modalities (for example, each telephony network typically makes use of different short numbers to be dialed for accessing various IN services); ease of use of the IN services is thus jeopardized. For example, in order to contact a voice mail-box from a visited network, the user may have to dial a long number, instead of the customary short number used in the home network; similarly, in order to set up a call for a user with a pre-paid terminal, a first telephone call from the home network to the pre-paid terminal may have first to be set up, followed by a second telephone call from the home network to a destination extension.
European patent application no. EP 1124388 relates to a relay service control procedure that enables network operators and/or service providers to provide home services to the visiting user, who is located in a visited serving network, when the visited serving network is not equipped to offer the home services. This is accomplished by enabling the visited serving network to expand their portfolio of available wireless services on an as needed basis. It obtains the needed Service Logic Program (SLP) from the Service Control Function of the user's home network or the Service Control Function of any other supporting network in the wireless communication system that supports the requested service. The visited serving network executes the relayed Service Logic Program in its Service Control Function and directly controls the provision of the requested service to the visiting user.
Recently, in order to facilitate the management of IN services in cases of roaming, a standard referred to as Customized Application for Mobile network Enhanced Logic (CAMEL) has been prepared, and a phase I of the CAMEL standard is implemented in some mobile telecommunication networks at the moment.
According to the CAMEL standard, the subscription data (stored in the Home Location Register—the HLR—of the home network) of a generic user which is a subscriber of an IN includes OCSI (Original CAMEL Subscription Information) data, which are exploited when that user roams in a different network for the management of the IN services. The OCSI data include, in particular, address data of a Service Control Function (SCF) in the home network and a service key. The SCF is a network's functional entity that contains the CAMEL service logic for implementing one or more operator-specific IN services. The service key identifies the service which is intended to be made available to the user when in roaming in other networks.
Essentially, CAMEL phase I provides a standardization of messages sent from a visited network in which the terminal is present, to the home network. This standardization provides a first step towards access of IN services from another network.
PCT patent application no. WO 00/65854 relates to a method and system for distributing IN services to a mobile network, wherein a Service Trader Function (STF) is provided in the mobile network. The STF may be a function provided in the HLR or may be arranged as a separate network element connected to the HLR. The STF stores and updates locations of distributed IN services. Furthermore, an information about networks and service control points to which IN services have been downloaded may be contained in the STF. In operation, when a location update procedure is performed between the HLR and the VLR of the visited network, the subscriber's service sets are checked by the HLR. Based on the IN service information returned from the STF, the ma updates its service trigger information such as the Camel Subscription Information (CSI) in the subscriber data, and supplies it to the VLR of the visited network. Thereby, the MSC of the visited network may obtain the corresponding updated subscriber trigger information from its VLR, such that a required IN service can be executed at the visited network. The IN service may have been already downloaded to the visited network at an, earlier time, or it may be as well downloaded in the course of a triggering or location update. According to alternative embodiments, the STF may be contacted by the VLR or by the MSC of the visited network.
PCT patent application no. WO 03/032656 relates to a method for accessing an IN service implemented in a first telecommunication network by a terminal, which is subscribed to the first network and which is roaming in a second telecommunication network. The method comprises the steps initiated by a IN service request number sent from the terminal and received in a Service Switching Function (SSF) in the second network; sending an IN service request detect message from the SSF to a first Service Control Function (SCF) in the first network, based on the number; sending a redirect message from a second SCF to the SSF, the redirect message comprising a command to establish a connection and a destination number associated with the IN service to be accessed; and accessing the IN service from the SSF by dialing an access number comprising the destination number.